There is a need for new processes for the solution polymerization of high molecular weight ethylene-based polymers (for example, EPDM), using high polymerization temperatures (for example, greater than, or equal to, 160° C.). Conventional solution polymerizations are typically run at temperatures less than 160° C., and higher temperatures for the polymerization high molecular weight and high comonomer incorporation cannot be achieved, due to limitations with current polyolefin catalyst technology.
Some polyolefin polymerization processes and associated catalysts are described in the following references. International Publication WO2007/136497 discloses a catalyst composition comprising one or more metal complexes of a multifunctional Lewis base ligand, comprising a bulky, planar, aromatic- or substituted aromatic-group, and polymerization processes employing the same, for example, continuous, solution polymerization of one or more α-olefins at high catalyst efficiencies.
International Publication WO2007/136494 discloses a catalyst composition comprising a zirconium complex of a polyvalent aryloxyether. Such complex is used in a continuous solution polymerization of ethylene, one or more C3-30olefins, and a conjugated or nonconjugated diene, to prepare interpolymers having improved processing properties.
International Publication WO2007/136496 discloses metal complexes of polyvalent aryloxyethers, appropriately substituted with sterically bulky substituents that possess enhanced solubility in aliphatic and cycloaliphatic hydrocarbons. When such complexes are employed as catalyst components for the polymerization of ethylene/α-olefin copolymers, they produce products having reduced I10/I2 values.
International Publication WO2006/020624 discloses a supported, heterogeneous catalyst composition for use in the polymerization of addition polymerizable monomers, to form high molecular weight polymers. The catalyst composition comprises the following: 1) a substrate comprising a solid, particulated, high surface area, surface modified, inorganic oxide compound, 2) a Group 4 metal complex of a bis(hydroxyarylaryloxy) ligand; and optionally 3) an activating cocatalyst for the metal complex. International Publication WO2007/136493 discloses a process for the polymerization of propylene, optionally ethylene, and further, optionally, one or more C4-30 α-olefins and/or one or more conjugated or nonconjugated dienes, under continuous, solution polymerization conditions, to prepare a high molecular weight polymer or interpolymer. The process comprising conducting the polymerization in the presence of a catalyst composition comprising a hafnium complex of a polyvalent aryloxyether.
International Publication WO2007/136495 discloses a catalyst composition comprising a zirconium complex of a polyvalent aryloxyether, and an alumoxane, and polymerization processes employing the same, and especially the continuous, solution polymerization of ethylene and one or more C3-30 olefins or diolefins, to prepare copolymers having reduced cocatalyst by-product content. International Publication WO2007/136506 discloses a catalyst composition comprising a zirconium complex of a polyvalent aryloxyether, and a polymerization process employing the same, and especially a continuous, solution polymerization of ethylene and one or more C3-30 olefins or diolefins, to prepare interpolymers having improved processing properties. See also the following references for polymerization processes, catalysts and/or polymer products: WO2011/002998, WO2011/002986, WO2009/067337, WO/2011/008837, and WO/2010/033601.
However, there remains a need for new polymerization processes that can be used to form high molecular weight ethylene-based polymers with good comonomer incorporation. There is a further need for such processes that can operate at higher temperatures (T>170° C.), enabling higher molecular weight polymers to be produced at lower, in-reactor viscosities. These needs have been met by the following invention.